CRUCIFERAE. 127 



habitually or frequently remain undivided below, we may add the genus 

 Streptanthus (Plate 61, fig. 4). Although these able botanists do not allude 

 to the analogous case of Fumariaceae, yet it is perfectly evident that they 

 would apply the same principle to the explanation of the anomaly in that 

 family. The six anthers are all alike and two-celled. 



The gynsecium consists of two united carpels, which stand right and left 

 as respects the axis of inflorescence, or one before each of the lateral sepals. 

 The peculiarity of the silique consists in its being two-celled, while the pla- 

 centae are strictly parietal. The explanation of this long since indicated by 

 Brown, and by Lestiboudois, is doubtless the true one ; namely, that the 

 false dissepiment is an extension of the parieties of the carpels, or, so to 

 say, of the epicarp of each, stretching inwards beyond their ovuliferous 

 edges, so as to form, sometimes a narrow border, as in Selenia (Plate 67), 

 &c , but commonly a perfect partition by their union in the centre. The 

 line of junction is frequently indicated by a median nerve (Plates 53, 55, 57, 

 64). This partition, however thin, is separable into its two component la- 

 mella;, composed apparently of a single stratum of compressed cells, which 

 are of different forms in different plants. Besides this areolation, the par- 

 tition is sometimes veiny, or traversed, more or less copiously, by " tubes 

 having the appearance and ramification of the veins of a leaf." These dif- 

 ferences were pointed out by Mr. Brown, and turned to account in distin- 

 guishing genera.* We have endeavoured to figure the principal forms of 

 areolation which are presented by the species we have illustrated ; but are 

 not prepared to offer any opinion respecting the value of this character. 



In several Cruciferae, this partition is altogether wanting, especially in the 

 Isatideae, where the pod is indehiscent and only 1-2-seeded, and in Cakile 

 (Plate 74) and its allies, in which the pod is transversely divided and joint- 

 ed. In the dehiscent genera, the two valves always separate from the fili- 

 form placentae, which form the frame (rcphtm) for the partition, and bear 

 the persistent style or stigma. 



The styles, if any, are always consolidated into one. The two stigmas 

 are either combined, or more or less distinct (2-lobed) ; and the lobes are 

 anterior and posterior, or are placed over the parietal placentas, and not over 

 the cells; just as happens in most Papaveraceae, and in many other cases of 

 parietal placentation. This, along with the abnormal partition and dehis- 

 cence, gave rise to some ingenious hypotheses respecting the structure of the 

 Cruciferous fruit, which need not be here recounted, since their foundations 



"5. Finally, certain Cruciferae, instead of returning to the quaternary type, 

 recede from it. Their single stamens undergo a change analogous or very sim- 

 ilar to that of the double pair. One of us lias observed flowers of Matthiola in- 

 cana, in which the single stamens were cleft throughout their entire length 

 each portion being provided with half an anther and half a filament. M. Lesti- 

 boudois speaks of a Cheiranthus Cheiri in which these stamens were completely 

 geminated, not laterally as the longer pair, but from without inwards. M. Se- 

 ringa met with a flower of the same species (var. grandiflora) which had the 

 lower stamens ' didoubldes ejartcment comma les sup&rieures.' " — Moq.-Tand. tfc 

 Webb, in 1. c. p. 5, and p. 6, 7. 



* Ohserr. PI. Oudney, Denham,ty Clappcrlon, p. 12. cl Bcq, 1826 



